Question

The 3rd term of an ap.is 18 and 7th term is 30 and find the sum.of 17th term

Answer 1

Answer:

sum of 17th term=612

Step-by-step explanation:

a+2d=18

a=18-2d

a+6d=30

18-2d+6d=30

18+4d=30

4d=30-18

4d=12

d=12/4 = 3    and a=18-6=12

sum of 17th term=n/2[2a+(n-1)d]

                           =17/2[2×12+(17-1)3]

                           =17/2[24+(16)3]

                           =17/2[24+48]

                           =17/2[72]

                           =17×36

                           =612